Imaging Guide to Inner Ear Malformations: An Illustrative Review.

Inner ear malformation (IEM) with associated sensoryneural hearing loss (SNHL) is a major cause of childhood disability. Computed tomography (CT) and magnetic resonance imaging (MRI) imaging play important and often complementary roles in diagnosing underlying structural abnormalities and surgical planning allows for direct visualization of the cochlear nerve and is the preferred imaging modality prior to cochlear implantation. CT is helpful to assess osseous anatomy and when evaluating children with mixed hearing loss or syndromic associations. When reviewing these cases, it is important for the radiologist to be familiar with the key imaging features. In this article, we will present the imaging findings associated with different inner ear malformations associated with congenital sensorineural hearing loss.

Loss of Tsc1 in cerebellar Purkinje cells induces transcriptional and translation changes in FMRP target transcripts.

Tuberous sclerosis complex (TSC) is a genetic disorder that is associated with multiple neurological manifestations. Previously, we demonstrated that Tsc1 loss in cerebellar Purkinje cells (PCs) can cause altered social behavior in mice. Here, we performed detailed transcriptional and translational analyses of Tsc1-deficient PCs to understand the molecular alterations in these cells. We found that target transcripts of the Fragile X Mental Retardation Protein (FMRP) are reduced in mutant PCs with evidence of increased degradation. Surprisingly, we observed unchanged ribosomal binding for many of these genes using translating ribosome affinity purification. Finally, we found that multiple FMRP targets, including SHANK2, were reduced, suggesting that compensatory increases in ribosomal binding efficiency may be unable to overcome reduced transcript levels. These data further implicate dysfunction of FMRP and its targets in TSC and suggest that treatments aimed at restoring the function of these pathways may be beneficial.

Factors influencing the acute pentylenetetrazole-induced seizure paradigm and a literature review.

OBJECTIVE: To confirm the critical factors affecting seizure susceptibility in acute pentylenetetrazole (PTZ) mouse epilepsy models and evaluate the prior literature for these factors. METHODS: Serial cohorts of wild-type mice administered intraperitoneal (IP)-PTZ were aggregated and analyzed by multivariate logistic regression for the effect of sex, age, background strain, dose, and physiologic stress (i.e., EEG implantation and/or single-housing) on seizure response. We assessed the reporting of these factors in a comprehensive literature review over the last 10 years (2010-2020). RESULTS: We conducted aggregated analysis of pooled data of 307 mice (220 C57BL/6J mice and 87 mixed background mice; 202 males, 105 females) with median age of 10 weeks (range: 6-49 weeks) with acute PTZ injection (dose range 40-65 mg/kg). Significance in multivariate analysis was found between seizures and increased PTZ dose (odds ratio (OR) 1.149, 95% confidence interval (CI) 1.102-1.205), older age (OR 1.1, 95% CI 1.041-1.170), physiologic stress (OR 17.36, 95% CI 7.349-44.48), and mixed background strain (OR 0.4725, 95% CI 0.2315-0.9345). Literature review identified 97 papers using acute PTZ-seizure models. Age, housing, sex, and background were omitted by 61% (59/97), 51% (49/97), 18% (17/97), and 8% (8/97) papers, respectively. Only 17% of publications specified all four factors (16/97). INTERPRETATION: Our analysis and literature review demonstrate a critical gap in standardization of acute PTZ-induced seizure paradigm in mice. We recommend that future studies specify and control for age, background strain, sex, and housing conditions of experimental animals.

Intervertebral Disc Calcification and Klippel-Feil Syndrome.

Intervertebral disc calcification is rare in the pediatric population and is associated with sudden neurological manifestations. Although commonly symptomatic, conservative management yields excellent prognosis in the vast majority of cases. The following case illustrates the finding of intervertebral disc calcification in a patient with vertebral body segmentation anomaly consistent with Klippel-Feil Syndrome. As both entities are associated with potential neurological sequelae, this case of coexistent pathologies highlights the importance of recognizing the potential presence of intervertebral disc calcifications in pediatric Klippel-Feil Syndrome patients.

Radiologist's Primer on Imaging of Common Hereditary Cancer Syndromes.

Recent advances in pathology and genetics have improved our understanding of the pathogenesis of inherited and sporadic malignancies. Detailed studies of hereditary cancer syndromes-which contribute to 5%-10% of the overall cancer burden-have shed new light on the important role of genetic abnormalities in tumor metabolism, oncologic pathways, and clinicobiologic behavior. Many inherited cancer syndromes are characterized by development of pathognomonic histotypes of neoplasms in specific target organs. Cross-sectional imaging plays an integral role in diagnosis, screening, surveillance, and treatment of patients with a wide spectrum of cancer syndromes. This article focuses on the imaging spectrum of select hereditary cancer syndromes, featuring imaging features of associated common and uncommon tumors and conditions in each syndrome, along with screening and surveillance recommendations for each condition. MRI has proved to be a useful screening modality in such patients, as these patients are often young and require prolonged screening; MRI has the added advantage of better soft-tissue contrast without ionizing radiation. The whole-body MRI protocol is also briefly discussed. The radiologist is sometimes the first physician to encounter such patients, and knowledge of these syndromes can help identify these patients earlier and impact their care by timely diagnosis and intervention. This also benefits the family members, as they can also undergo genetic testing and obtain an early diagnosis and screening. ©RSNA, 2019.

Imaging of Skeletal Disorders Caused by Fibroblast Growth Factor Receptor Gene Mutations.

Fibroblast growth factors and fibroblast growth factor receptors (FGFRs) play important roles in human axial and craniofacial skeletal development. FGFR1, FGFR2, and FGFR3 are crucial for both chondrogenesis and osteogenesis. Mutations in the genes encoding FGFRs, types 1-3, are responsible for various skeletal dysplasias and craniosynostosis syndromes. Many of these disorders are relatively common in the pediatric population, and diagnosis is often challenging. These skeletal disorders can be classified based on which FGFR is affected. Skeletal disorders caused by type 1 mutations include Pfeiffer syndrome (PS) and osteoglophonic dysplasia, and disorders caused by type 2 mutations include Crouzon syndrome (CS), Apert syndrome (AS), and PS. Disorders caused by type 3 mutations include achondroplasia, hypochondroplasia, thanatophoric dysplasia (TD), severe achondroplasia with developmental delay and acanthosis nigricans, Crouzonodermoskeletal syndrome, and Muenke syndrome. Most of these mutations are inherited in an autosomal dominant fashion and are gain-of-function-type mutations. Imaging plays a key role in the evaluation of these skeletal disorders. Knowledge of the characteristic imaging and clinical findings can help confirm the correct diagnosis and guide the appropriate molecular genetic tests. Some characteristics and clinical findings include premature fusion of cranial sutures and deviated broad thumbs and toes in PS; premature fusion of cranial sutures and syndactyly of the hands and feet in AS; craniosynostosis, ocular proptosis, and absence of hand and foot abnormalities in CS; rhizomelic limb shortening, caudal narrowing of the lumbar interpediculate distance, small and square iliac wings, and trident hands in achondroplasia; and micromelia, bowing of the femora, and platyspondyly in TD. ©RSNA, 2017.

Stroke-like migraine attacks after radiation therapy syndrome: Case report and review of the literature.

A 26-year-old female presented with vision loss accompanied by migraine-like headaches. A contrast-enhanced magnetic resonance imaging of the brain was performed which revealed findings suggestive of stroke-like migraine attacks after radiation therapy (SMART) syndrome. SMART syndrome is a delayed complication of brain radiation characterized by neurologic symptoms including migraine-like headaches, seizures, and hemispheric impairment. The purpose of this article is to make the readers aware of this rare complication of brain irradiation. Appropriate diagnosis of SMART syndrome is essential to avoid invasive tests.

Demystifying Orbital Emergencies: A Pictorial Review.

Imaging of the orbit plays an important role in the workup of orbital emergencies. Orbital imaging is particularly useful in the emergency department, where clinical history and physical examination may be limited or delayed until the exclusion or treatment of more life-threatening conditions. Cross-sectional orbital imaging with multidetector computed tomography (CT) and magnetic resonance (MR) imaging is commonly performed in addition to ultrasonography. In an emergent setting, CT is the preferred modality when evaluating for intraorbital foreign bodies, fractures, or calcifications within a mass lesion. MR imaging is typically the modality of choice for orbital pathologic conditions, owing to its superior ability to delineate the orbital soft tissues and visual pathways. CT and MR imaging together may supplement clinical evaluation by helping establish an accurate diagnosis, providing an objective assessment of disease extent and progression, and assisting in pretreatment planning. Orbital emergencies have a spectrum of cross-sectional imaging findings in four major categories: infection, trauma, vascular disease, and inflammation. Use of a systematic approach to these entities will assist the radiologist with identifying immediate threats to vision and thereby facilitate prompt clinical management. Familiarity with the clinical presentations also improves the radiologist's diagnostic confidence and role in guiding patient care. This article reviews imaging protocols, relevant orbital anatomy, the role of CT and MR imaging, and key imaging findings of orbital emergencies that the radiologist must know. © RSNA, 2017.

Posterior fossa syndrome with delayed MR evidence of unilateral superior cerebellar peduncle (SCP) damage.

Posterior fossa syndrome (PFS) is a well-known sequela of midline posterior fossa tumor resection. Patients typically exhibit transient behavioral, motor, and oculomotor disturbances that resolve within a few weeks to several months after surgery. The underlying pathophysiology of PFS is not completely understood, but contemporary literature has implicated injury to the dentate nucleus and/or exiting dentatothalamocortical fiber bundles as a causative factor. The authors present a case of a young male who developed a delayed variant of PFS typified by motor deficits and demonstrated diffusion restriction in the ipsilateral superior cerebellar peduncle. Because the correlation between PFS and the superior cerebellar peduncle injury is poorly described in the literature, particularly with regard to relevant radiographic imaging, the authors of this report hope their findings will contribute to that insufficient body of evidence.

Pediatric Mediastinal Tumors and Tumor-Like Lesions.

This article reviews the imaging findings of pediatric mediastinal tumors and tumor-like lesions. The classification of the mediastinum is discussed with normal imaging appearance of the thymus in pediatric age group followed by a discussion on multiple mediastinal lesions in different compartments with emphasis on their imaging characteristics.

Imaging spectrum of facial nerve lesions.

The facial nerve is affected by a wide variety of pathologies, including congenital, traumatic, inflammatory, and neoplastic conditions. Imaging plays a vital role in the diagnosis of these pathologies. The facial nerve has a complex anatomy and course. A strong grasp of normal facial nerve anatomy is essential for the radiologist to maintain a high level of diagnostic sensitivity. This article details the normal imaging anatomy of the facial nerve and the imaging features of common facial nerve pathologies.